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Journal of Sensors
Volume 2011, Article ID 827969, 6 pages
Research Article

Wireless Moisture Sensor Using a Microstrip Antenna

Division of Electrical Engineering and Computer Science, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan

Received 1 May 2011; Revised 21 September 2011; Accepted 23 September 2011

Academic Editor: P. Siciliano

Copyright © 2011 Tatsuo Toba and Akio Kitagawa. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A wireless moisture sensor has been developed on the basis of the backscatter characteristic of the microstrip antenna, which works in the far field without a battery. This study aims to develop a wireless sensor with a long communication distance and to apply the wireless applications, such as monitoring the moisture in the wrapped products and surface adsorption of hydrogen peroxide in the biological isolation systems. The dropwise addition of the distilled water on the cleaning tissue is clearly detected by the measurement of the backscattered power from the sensor at the frequencies of 0.954 GHz and 2.45 GHz. The ratio of the backscattered power in two frequency bands can be used as an index to measure moisture.